Detection and reporting of homozygosity associated with consanguinity in the clinical laboratory

The detection of consanguinity by the presence of multiple regions of homozygosity (ROH) is not an uncommon occurrence in clinical laboratories performing SNP microarray analysis. Reporting practices amongst laboratories are highly variable, due in part to differences in testing platforms, threshold parameters, language utilized, and laboratory policies. While guidance documents have provided a framework for detection and reporting practices, and will doubtless serve to harmonize the field, there are still many facets of the testing that remain at the discretion of the performing laboratory. Clinician and patient education remain a high priority. In the clinical laboratory, these homozygous segments are often examined to identify genes associated with a phenotype that matches that of the proband and autosomal recessive inheritance. While the detection of these ROH is possible with whole genome sequencing, it currently requires special algorithms be utilized, an uncommon practice in most clinical laboratories currently performing this type of testing.